Standards/cruisers are well-rounded and comfortable. The handle-bar styling feels natural (like a bicycle) and is the preferable styling for the general transportation you'd do with a car. Choppers and harleys are great for roadtrips, and sports-bikes are great for racing and on the highway, but the standard is a natural position, allowing a new rider to enjoy the experience, focus on traffic, safety, and riding technique instead of trying to manage a heavy chopper or harley, or staying balanced and aware of everything around you on the forward-tilt of a sports bike.
-Pay least amount for given level of performance
-Comfortable in all riding situations, yet more maneuverable than a chopper or harley
-Least likely to lay down, or have an accident with another vehicle
-Aggressive body styling looks cool
-Usually outfitted with higher performance (read: acceleration) parts
-Uncomfortable in traffic or for 40+ minute rides and hard on the wrists
-Poor low-speed turning ability, which is why it's preferable for highway riding.
-Ideal for long distances (very comfortable and usually outfitted with convenient features for this)
-Heavy and more difficult to navigate in traffic
-Unimpressive gas mileage